Apparatus for mounting and dismounting piston rings



p 25, 1956 A. OSTERGAARD 2,763,922

APPARATUS FOR MOUNTING AND DISMOUNTING PISTON RINGS- Filed March 16, 1950 4 Sheets-Sheet A Anders Oflergaard- I N VEN TOR L ATTORNEYS Se t. 25 1956 A. OSTERGAARD 2,763,922

APPARATUS FOR MOUNTING AND DISMOUNTING PISTON RINGS Filed March 16. 1950 4 Sheets-Sheet 2 g e h E I: H

8,6 g I D 5 /7 4 l8 5 l6 2 l Anders Osfergaard INVENTOR i4 ATTORNEYJ Sept. 25, 1956 A. OSTERGAARD 2,763,922

APPARATUS-FOR MOUNTING AND DISMOUNTING PISTON RINGS Filed March 16. 1950 4 Sheetts-5het 3 Andrs 0s fergaard I N VENTOR A", ATTORNEYS p 1956 A. OSTERGAARD 2,763,922

AFPARATUS FOR MOUNTING AND DISMOUNTING PISTON RINGS Filed March 16, 1950 4 Sheets-Sheet 4 Fig. 7

Anders Osfergaad 1 INVENTOR Pskl'.

8 ATTORNEYj APPARATUS FOR MOUNTING AND DISMOUNT- ING PISTON RINGS Anders Ostergaard, Copenhagen, Denmark Application March 16, 1950, Serial No. 149,985

Claims priority, application Denmark March 18, 1949 Claims. (Cl. 29-223) The present invention relates to an apparatus for the mounting and dismounting of piston rings by distention of the latter by actuating the ends of the piston rings with moments which act for expanding or distending the ring, the apparatus being provided with a pair of claws or application parts intended for being placed on the ends of the piston rings, each of said claws or parts being by the operation of the apparatus made to actuate its ring end with a pair of inwardsand outwards-directed forces, respectively, each claw being at two points, which form points of application for the transmission of forces to the claw, rotatably connected to its rod of a pair of rods which at the end facing away from the claw are connected to an operation or actuating device which in a uniform way can actuate the rods through said points of connection.

An apparatus of the kind referred to is known from the specification of German Patent 379,634, but this known apparatus is constructed in a way that necessitates comparatively large and heavy actuating members, so that the apparatus is expensive to produce and difiicult to operate.

An apparatus of the kind referred to is furthermore known from the specification of Swiss Patent 249,688, which apparatus is, however, also designed in a way that entails comparatively heavy actuating members, the apparatus being so constructed that the forces that through the actuating members are transmitted to said rods are transmitted in a direction which almost corresponds to the direction of the forces in said rods connected to the claws and will therefore be of approximately the same magnitude. The points of connection, moved at the operation of the apparatus, between the actuating members and said rods are furthermore moved in a direction corresponding substantially to the direction of the forces in the rods, which means that the forces occurring in" the actuation direction in the actuating members will increase substantially proportional to the rod force. Finally may be mentioned that the actuating device proper in the embodiment known, which applies a screw motion, is inexpedient, being designed in such a way that the operation is difiicult and inconvenient.

By the invention an apparatus of the kind mentioned is attained in which the drawbacks of the constructions known are avoided. A special advantage is that the great forces in the direction of actuation mentioned above are avoided. in accordance with the invention this is substantially attained by the operation member being designed in such a way and being so connected to the rods leading from the claws that the points of these rods located opposite to the points of application are brought to approach each other when the apparatus is actuated for the distention of the piston ring. .By designing the apparatus in accordance with the invention, a better utilization of the dimensions of the actuating members is attained, the force in the direction of actuation becoming of a magnitude that is considerably smaller than the forces in the rods, viz. the product of said rod forces r 2,763,922 Patented Sept. 25, 1956 into cosine of the angle between the direction of actuation and the direction of the forces in the rods or, as will be explained later in connection with the drawing, a quantity obtained by the composition of the rod forces into a resultant in the direction of actuation, whereby the force not only becomes dependent on the forces in the rods, but becomes dependent also on the angle of the rods to the direction of actuation.

The apparatus in accordance with the invention is hereby expediently so constructed that the points that are during the operation of the apparatus for the distention of the piston ring made to approach each other are moved towards each other in a direction which is at any rate approximately at right angles to the connection line between the points of application in the two claws of two correspondingly located rods.

The apparatus in accordance with the invention may furthermore advantageously be so constructed that the points of connection between the actuating device and the rods are in each of the two pairs of correspondingly located rods situated at a slight distance from each other or may coincide.

in accordance with a further development of the invention, at least one pair of the ends or connection points, facing away from the claws, of the two pairs of rods actuating the claws are prevented from turning in relation to each other, said rod ends or points of connection being hereby either coincident or so connected that said turning is prevented. Hereby is prevented that the reactions from the forces in the two adjacent correspondingly located rods, which reactions act at right angles to the direction of actuation, may get out of line with each other, whereby a mutual turning of the two rod ends might occur, the apparatus thus being unstable.

The apparatus in accordance with the invention'may furthermore expediently be so designed that the line passing through the points of application in a claw intersects the connection line through the end points of the pertaining rods (connection points with the actuating device) in or in the vicinity of the centre of the piston ring, at any rate when the claws are located on the ring ends in the distented state of the ring. Hereby a uniform actuation of the ring ends during the whole of the distention of the piston ring is attained.

It is furthermore characteristic of the invention that the two rods leading from a claw are so adapted and fitted that, when the ring is in its distended state, they are parallel or practically speaking parallel, which may also be expressed so that the proportion between said two rod lengths corresponds to the proportion between the lengths located between each of the points of application in the claw of the two rods and the point of intersection between the line through said two points of application and the line through the end points of the rods (the points of connection with the actuation device), likewise when the ring is in its distended state.

moments it is also able to actuate the ends of the rings with single forces of a suitable order. For this purpose the rod systems are so constructed that the two rods in a rod system which are connected to the points of application of the pertaining claw have such directions in relation to each other, when the apparatus is mounted on the ring in the distended state of the latter, that at any rate in this state, when the forces and stresses are largest, the ring is actuated in an expedient way with regard to the avoidance of such stresses as involve the risk of breakage as well as with regard to the power of the ring of sealing against the cylinder wall after having been mounted in the cylinder.

The invention is illustrated on the accompanying drawing, where Fig. 1 shows an embodiment of the apparatus in accordance with the invention, the apparatus being shown mounted on a piston ring and viewed in the axial direction of the latter, I

Fig. 2 in a manner corresponding to Fig. 1 another embodiment,

Fig. 3 the apparatus shown in Fig. 2 viewed from the side of the piston ring,

Fig. 4 a section on line IV-IV in Fig. 2,

Fig. 5 in a manner corresponding to Figs. 1 and 2 still another embodiment,

Fig. 6 a section on line VI-VI in Fig. 5,

Fig. 7 shown diagrammatically the Iapparatus shown in Fig. 2 with indications of the latter in three different positions during the distention of the piston ring, and

Fig. 8 a graphic illustration of the moment to which the ring is subjected and the forces occurring in the apparatus as functions of the distention of the ring.

1 and 2 in Fig. 1 designate the ends of a piston ring on which ends claws 5 and 6, respectively, are mounted, having outwards-projecting arms 3 and 4, respectively. A and E designate points of application on the claw 5 for rods 1 and e, respectively, and correspondingly the points D and H on the claw 6 are points of application for rods g and h, respectively. The claws 5 and 6 are provided with hooks 7 and 8, respectively, which gn'p around the ends of the piston rings so that they can actuate the latter with outwards-directed forces. At some distance from the ends of the rings, the piston ring can be actuated by inwards-directed forces which may be transmitted through adjustment screws and 10, respectively, mounted in the claws. The rods 7 and g are at the points B and C secured rotatably to a nut member 11 which forms the nut for a screw 12 with .an operation handle 12a. Between the head of the screw 12 and the nut member 11, a sleeve member 13 is mounted, to which the rods 5 and h are rotatably connected at the points F and G.

The apparatus shown and described functions in the way that :after the mounting of the claws 5 and .6 on the piston ring ends 1 and 2, while thering is in its free position and the screw 12 partly screwed out of the nut member 11, the distention of the ring is performed by the screw 12 being screwed in, The screwforce produced hereby will be resolved into equal pulling forces in the rods 1 and g and into equal pressure forces in the rods 6 a h h Q p l and m ssur forces are transmitted to the claws 5 and6 at the points of aPPlioationA and D .3 a d H, respe i ly so t a ac ind idual c a receives pu orces t he P i t and D,. e pes=tively and pressure forces at the points E and H, ,respect vely. These pulling and pressure forces together form a sysm of f s Consisting o e l nd oppositely d re t moments and contingently single forces, acting on the claws, so that when one claw is subjected to a moment and a single force in a certain direction, the other claw is subjected to an equal moment and an equal single force in the opposite direction. The order of the single force in relation to that of the moment is determined by the geometrical design of the apparatus and is chosen so that after having been mounted in the cylinder the ring will to as wide an extent as possible be suited for its purpose. Said system of forces is transmitted through the claws to the ends of the rings, whereby the ring will be distended. During this distention, the friction in the apparatus will cause an alteration of the system of forces actuating the ring ends in such a way that said single force will become slightly different from that calculated.

It appears from Fig. 1 that the acute angles between the lines E-F and G--H, and A-B and C-D, respectively, on one side and the direction of the screw force on the other side will increase during the distention of the ring. With the increased distention of the ring, the

forces in the rods will also be increased, but by composing the rod forces into a resultant in the direction of the axis of the screw it will be seen that this resultant gets a slighter increase, the size of the resultant being equal to twice the rod force multiplied by cosine of the momentary value of the angles mentioned above which increase during the distention and the cosines of which will therefore decrease. By a suitable design of the apparatus it is possible to make the product of the force in the rods and cosine of said angle vary in such a way that the apparatus becomes exceedingly convenient to operate.

In Fig. l is shown that the lines E.A and F*B intersect at a point that coincides with the point of intersection for the lines HTD and GPC, which point may be the centre of the piston ring or a point in the vicinity of the centre. The two points of intersection mentioned may, however, also be located at some distance from each other. This will at any rate be the case in an embodiment of the apparatus differing from that shown in Fig. 1 in that the points B and C coincide.

The embodiment shown in Figs. 2 and 3 is substantially only different from that shown in Fig. 1 by a slightly different design of the claws 5 and 6 and by the points B and C coinciding and by the points F and G coinciding, too. As appears from Fig. 3, the rods h are mounted on the outside of the rods e, and the same applies to the rods g and f. The h and g are thereby joggled at the end where they are connected to the claw 6. Consequently the apparatus becomes somewhat broader than the apparatus shown in Fig. 1 where all the rods :2, f, g, and h can be located in the same plane. The claws 5 and 6 abut in accordance with Figs. 2 and 3 on the outside of the piston ring with abutments 15 and 16, while they grip the inside of the ring by means of clamping members 17 and 18, respectively, with pertaining nuts, see also Fig. 4. The members shown are adjustable in accordance with the height of the ring and may be applied independently of the manner in which the lock in the piston ring is designed. They are furthermore changeable so that other claws may be mounted for use for rings with especially designed locks.

In the embodiment shown in Figs. 5 and 6, a pair of levers '19 and 20 are used instead of a screwing device for effecting the necessary actuation for the distention of the piston ring. The two levers 19 and 20 are at one end pivoted on a common pivot 14 to which the ends of the two correspondingly located rods f and g are connected, so that the end points or connection points B and C of these rods will thus coincide with each other and with the pivot point 14. The two other correspondingly located rods eand h have also coinciding end points F, G so as to be connected by a common pin 26, to which one end of a pair of connection rods 21 and 22 is furthermore connected rotatably, the other end of which rods is rotatably connected to the levers 19 and 20, respectively, by means of pins 23 and 24, respectively, mounted in said levers, 19a and 20a are recesses in the levers for the rods 21 and 22. 25 designates a wire spring, the ends of which are secured on pins 27 and 28, respectively, mounted in the rods 1 and g and which are otherwise carried along the lower ends of the levers 19 and 20, as appears from Fig. 5. This spring acts for moving the claws 5 and 6 away from each other and entails the advantage that at the insertion of the claw hooks 7 and 8 between the ends of a piston ring the apparatus will automatically be pressed into abutment on the ends of the piston ring and be secured in this position, so that after this the operation of the apparatus is very easy.

The apparatus shown and described otherwise functions in the following way. When, as mentioned, the apparatus has been mounted in its place on a piston ring, the two free ends of the levers 19 and 20 are moved towards each other under rotation of the two other ends around the pivot 14. Hereby the connection rods. 21 and 22 are turned so that the angle between. them decreases, whereby their connection pin 26 is led downwards towards the pivot 14, and thereby the same eifect is attained as was attained in the embodiments of the apparatus described above. The present embodiment entails the special advantage that the necessary actuation force will on account of the special manner of eifecting the transmission through the connection rods 21 and 22 decrease towards the end of the motion on account of the decrease of the angle between the connection rods.

The embodiment shown in Figs. and 6 may be varied in difierent ways, as e. g. the pivot 14 need not coincide with the end points B and C which may be located on either side of the pivot 14. Similar facts apply to the end points F and G and the lower end points of the connection rods 21 and 22 (the pin 26). In case of larger dimensions of the apparatus, a transverse screw device may be mounted for causing the necessary motion of the levers 19 and 20.

The apparatuses shown in Figs. 2-4 are expediently also designed in such a way that the connecting lines between the points of application E and A, H and D, respectively, interest in the centre of the piston ring or at a point in the vicinity of said centre, at any rate in the distended state of the ring.

In Fig. 7 a diagrammatical illustration is shown of an apparatus in accordance with Fig. 2 in three different positions during the distention. The distance between the points of application A and D situated closest to each other in the two red systems is designated by y with indexes O, 1, and 2, and corresponding indexes are used for the diiierent points and for the distance a between the rods 1 and e which lead from the points of application A and E and are at any rate approximately parallel and for these rods and for the distance d between the end points F and B of the rods.

As will be seen, the distance a increases at the distention of the ring, i. e. while at the same time the distance y increases and the distance d decreases, and this entails that the forces Psi; in the rods e and f increase slowlier than the moment in the piston ring. As already appears from what has been stated in connection with Fig. 1, the resultant of the rod forces in the direction of the axis of the screw increases still slowlier on account of the constant increase of the angle between the direction of the axis of the screw and the direction of the rods e and f, which in turn means that the necessary force Pskr in the screw 12 increases to a slighter degree than the moment in the piston ring. By a suitable design of the apparatus, it will even be possible from a certain point during the distention to obtain a declining force in the operation member as appears from the curve for the screw force Pskr in Fig. 8 which shows this force besides the rod forces Psi; and the ring moment Mb as functions of the distance y which is a measure for the distention.

The moment Mb is plotted on the basis of the following formula:

-EXIX 6 The screw force Pskl is obtained by the composition of the rod forces in accordance with the parallelogram method as already mentioned.

By, as already mentioned, making the screw force de crease towards the end of the distention, a position of rest can here be obtained, which is a special advantage in such embodiments where the operation member is not selfblocking in all positions, Taken as a whole, said fact is a great advantage, the force necessary for the operation becoming comparatively small, so that even the largest ring can without difliculty be distended quickly and easily. It is also an essential advantage that on account of the comparatively small force the operation members can be dimensioned almost solely from aesthetical points of view, which to a higher degree makes a standardization possible, which of course is of great importance for the production.

The constructions of the apparatus in accordance with the invention shown and described are given only as embodiment examples, it being possible, with regard to details, to design the apparatus also in other ways within the scope of the invention.

I claim:

1. A tool for expanding split piston rings by engaging the ends thereof comprising a pair of jaw members having ring engaging portions adapted to overlie and engage the end portions of a split piston ring and having arm portions laterally outstanding therefrom, a first innermost pair of rod members having outer ends pivotally connected to the jaw members adjacent the inner ends of the arm portions, a second pair of outermost rod members of greater length than the first pair of rod members and having outer ends pivotally connected to the arm portions adjacent the outer ends of the arm portions, an actuating means situated between and spaced outwardly from the ring engaging portions of the jaw members and including a first means and a second means movable relative to each other in a direction toward and away from the jaw members, said first pair of rod members and said second pair of rod members being disposed in substantial parallelism and having inner ends pivotally connected to the first means and the second means, respectively, of the actuating means, said actuating means being operative for simultaneously moving the inner pivoted ends of the first pair of rod members and the second pair of rod members toward and away from each other to move the pairs of rod members relatively in opposing longitudinal directions and actuate the jaw members to move them apart and together, said pivot points of the outer ends of the first and second pairs of rod members lying in coinciding lines which intersect on the side of the jaw members that abuts the piston ring.

2. A tool as claimed in claim 1, wherein the pivot points of the inner ends of both pairs of rod members lie in close proximity to the axis of symmetry of the tool.

3. A tool as claimed in claim 1, wherein the pivot points of the inner ends of both pairs of rod members are movable towards and away from each other in a direction substantially coinciding with the connection lines between said pivot points.

4. A tool as claimed in claim 1, wherein at least for one of the two said pairs or rod members, the distance between the two points in which the rod members of such pair are pivoted to the actuating means is smaller in any position of the tool than the distance between the two points in which the rod members are pivoted to the jaw members.

5. A tool as claimed in claim 1, wherein the actuating means includes an internally threaded nut member and an axially aligned longitudinally spaced sleeve, a spindle having a threaded portion threadingly engaged in the nut member and rotatable in said sleeve, a head on said threaded spindle engaging the sleeve to move the sleeve relative to the nut member; the two pairs of rod members being pivotally attached to the nut member and to the sleeve, respectively.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS Martin June 19, 1906 Moudy Dec. 5, 1916 Troutrnan Oct. 3, 1922 Kabanuck Sept. 4, 1923 Ling Apr. 17, 1928 8 Berkman Dec. 11, 1934 Gunderson Jan. 8, 1935 Kuert Nov. 29, 1949 FOREIGN PATENTS Germany Apr. 2, 1921 Netherlands Sept. 15, 1938 

